Electric System Malfunction
03-19-2023, 04:44 AM
#771
AudiWorld Member
The supercapacitors could be described as a bridge between the electrolytic capacitor and rechargeable batteries. They supply energy fast, recharge fast and their life is much longer than the batteries. As far as I know, the SCAP installed in SQ8 is not a "pure" battery, it i a hybrid type of supercapacitor which contains elements of a lithium-ion battery. That is why this type of SCAP is ideal to supply roll stabilisation or starters.
Butt to supply the electric compressors in TDI or even to support ICE for a long time there is still a need of battery which will last a long time at constant voltage.
Butt to supply the electric compressors in TDI or even to support ICE for a long time there is still a need of battery which will last a long time at constant voltage.
I have sat back and watched this SCAP conversation with interest. From a pure electrical engineering standpoint a capacitor bank however large, will not act as or replace a battery. By nature LiFePo4 (commonly referred to as just LiFe) batteries have many advantages over lithium-ion (Li-Ion) batteries. They weigh less, have better charge and discharge characteristics both in terms of cycle life (they last 4-5x longer) and safety (less likely to self-ignite if subjected to over-charging or excessive heat as happens occasionally in laptops and other such devices). Like Li-Ion batteries they require zero maintenance. Capacitors are often used across battery terminals in DC charging circuits to smooth out voltage fluctuations when for example an alternator switches on to charge a battery causing the voltage to jump up, or when the battery voltage jumps down under load during engine starting. So @a75 's post that the so-called SCAP is large capacitors in combination with a 48 Volt LiFePo4 battery makes perfect sense, and would certainly be a far more robust engineering solution than a 48 Volt Li-Ion battery alone.
Now we just need someone to rip an "SCAP" apart to confirm exactly what's inside!
Last edited by BRITinUS; 03-19-2023 at 04:59 AM.
03-19-2023, 07:05 AM
#772
AudiWorld Super User
I have sat back and watched this SCAP conversation with interest. From a pure electrical engineering standpoint a capacitor bank however large, will not act as or replace a battery. By nature LiFePo4 (commonly referred to as just LiFe) batteries have many advantages over lithium-ion (Li-Ion) batteries. They weigh less, have better charge and discharge characteristics both in terms of cycle life (they last 4-5x longer) and safety (less likely to self-ignite if subjected to over-charging or excessive heat as happens occasionally in laptops and other such devices). Like Li-Ion batteries they require zero maintenance. Capacitors are often used across battery terminals in DC charging circuits to smooth out voltage fluctuations when for example an alternator switches on to charge a battery causing the voltage to jump up, or when the battery voltage jumps down under load during engine starting. So @a75 's post that the so-called SCAP is large capacitors in combination with a 48 Volt LiFePo4 battery makes perfect sense, and would certainly be a far more robust engineering solution than a 48 Volt Li-Ion battery alone.
Now we just need someone to rip an "SCAP" apart to confirm exactly what's inside!
Now we just need someone to rip an "SCAP" apart to confirm exactly what's inside!
03-19-2023, 08:01 AM
#773
AudiWorld Member
When you say "size" do you mean dimensionally or or capacitance? I can see LiFePO4 being heavier if the two are dimensionally the same, but wouldn't same or similar capacitance be the goal in a replacement scenario?
03-19-2023, 10:33 AM
#774
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03-19-2023, 10:39 AM
#775
03-19-2023, 10:55 AM
#776
AudiWorld Member
The SCAP in the SQ8 is half the size of the LiIon. I doubt we could talk @Mrclopec into yanking it out and weighing it - his car is very new still.
Yes, please don't do that, @Mrclopec ! I just read a couple interesting articles on Li-Ion vs. LiFePO4, beyond the scope if this thread topic, and now understand why the shift may have taken place.
03-19-2023, 11:33 AM
#777
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Yes, please don't do that, @Mrclopec ! I just read a couple interesting articles on Li-Ion vs. LiFePO4, beyond the scope if this thread topic, and now understand why the shift may have taken place.
03-19-2023, 06:59 PM
#778
AudiWorld Super User
Apples to apples LiFePO4 is heavier. Classify it however you think is right, say in capacity/watt hour.
03-20-2023, 09:33 AM
#779
AudiWorld Member
Just a couple among many links, but do keep in mind these sites sell Li batteries. The biggest takeaways I see for automobiles would be the thermal runaway and cycle life benefits of LiFePO4 - although cycle life is out of phase with the planned obsolescence of most manufacturers these days.
https://blog.ecoflow.com/us/lifepo4-...ion-batteries/
https://volts.ca/blogs/educational/l...sphate-lifepo4
https://www.archasol.com/blog/lifepo...ich-is-better/
https://www.lithiumguys.com/lithium-ion-vs-lifepo4/
https://blog.ecoflow.com/us/lifepo4-...ion-batteries/
https://volts.ca/blogs/educational/l...sphate-lifepo4
https://www.archasol.com/blog/lifepo...ich-is-better/
https://www.lithiumguys.com/lithium-ion-vs-lifepo4/
03-20-2023, 09:58 AM
#780
Sian supercapacitator
I found following two links interesting. It is not necessary (using supercapacitator) to have a big energy storage to be able to regenerate energy from braking.
https://www.whichcar.com.au/advice/l...itor-explained
https://www.autoblog.com/2019/09/21/...6D9xum7xxVZ8xq
https://www.whichcar.com.au/advice/l...itor-explained
https://www.autoblog.com/2019/09/21/...6D9xum7xxVZ8xq